sqldf is an R package for runing SQL statements on R data frames, optimized
for convenience. The user simply specifies an SQL statement in R using data
frame names in place of table names and a database with appropriate table
layouts/schema is automatically created, the data frames are automatically
loaded into the database, the specified SQL statement is performed, the
result is read back into R and the database is deleted all automatically
behind the scenes making the database's existence transparent to the user
who only specifies the SQL statement.
WWW: https://code.google.com/p/sqldf/